Heretofore in the use of spindle adapters for tool holders, various structures have been used to removably mount and anchor a tool holder upon a power driven spindle incorporating an adapter assembly yieldably mounted upon the spindle including a series of balls cooperatively receiving and retainingly engaging the tool holder.
One of the difficulties in such assemblies is that the tool holder shank is slidably positioned within the axial bore of the spindle. Due to the looseness of the mounting of the tool holder shank within the spindle there is predictably some angular deflection of the tool holder and tool mounted thereon with respect to the longitudinal axis of the spindle. The difficulty with such mounting and assembly of the tool holder within and with respect to a power rotated spindle and employing a quick change adapter assembly upon the spindle is that there will be some angular deflection of the longitudinal axis of the tool holder and tool with respect to the fixed longitudinal axis of the spindle. This causes a corresponding angular deflection of the tool projecting from the holder and accordingly an inaccuracy in the drilling, boring or reaming of the tool with respect to a fixed workpiece.